I have been doing a fair bit of shooting with my Polaroid Land Camera, on Fujifilm FP-100C color instant film, and also FP-3000B monochrome film. I just found out that one can, with a little bit of bleach and work, reclaim the negative. This post at New55 Film provides instructions. (Of note is that New55 are going to produce a 4x5 instant film that gives a good negative as well as a print.) Picture of a reclaimed negative from there.